Organic EL display panel, organic EL display device having the same, and method for manufacturing organic EL display panel

Abstract

An organic EL display panel includes a wiring layer, a planarizing film above the wiring layer, and a plurality of light-emitting cells in a row. A pair of first banks are above the planarizing film to delimit lateral surfaces of the light-emitting cells. The planarizing film includes a plurality of recesses that are each formed between adjacent ones of the light-emitting cells and extend between the first banks. A plurality of organic light-emitting layers are each in one of the light-emitting cells between the pair of first banks. A plurality of second banks are connected to the first banks, and each comprise a same material as the first banks. Each of the second banks is above one of the recesses and has a shape that conforms to a profile of the one of the recesses so that the second banks are lower in height than the first banks.

What is claimed is: 
     
       1. An organic EL display panel, comprising:
 a wiring layer; 
 a planarizing film above the wiring layer; 
 a plurality of light-emitting cells in a row; 
 a pair of first banks above the planarizing film to delimit lateral surfaces of the plurality of light-emitting cells; 
 a plurality of organic light-emitting layers, each of the plurality of organic light-emitting layers being located in one of the plurality of light-emitting cells between the pair of first banks; and 
 a plurality of second banks, wherein 
 the planarizing film includes a plurality of recesses, each of the plurality of recesses between adjacent ones of the plurality of light-emitting cells and extending between the pair of first banks, 
 the pair of first banks and the plurality of second banks are connected and each comprise a same material, and 
 each of the plurality of second banks is above one of the plurality of recesses in the planarizing film and has a shape that conforms to a profile of the one of the plurality of recesses so that the plurality of second banks are lower in height than the pair of first banks. 
 
     
     
       2. The organic EL display panel according to  claim 1 , wherein
 each of the plurality of recesses in the planarizing film has a bottom that is lower than a bottom of each of the pair of first banks. 
 
     
     
       3. The organic EL display panel according to  claim 1 , further comprising:
 a plurality of cell-electrode layers, one of the plurality of cell-electrode layers being provided for each of the plurality of light-emitting cells, between the planarizing film and a corresponding one of the plurality of organic light-emitting layers, wherein 
 part of an edge portion of each of the plurality of cell-electrode layers is located inside a corresponding one of the plurality of recesses formed in the planarizing film, and 
 each of the plurality of second banks covers the part of the edge portion of a corresponding one of the plurality of cell-electrode layers located in the corresponding one of the plurality of recesses formed in the planarizing film. 
 
     
     
       4. The organic EL display panel according to  claim 3 , wherein
 the planarizing film has a plurality of contact holes, each of the plurality of contact holes interconnecting a corresponding one of the plurality of cell-electrode layers and the wiring layer, and 
 each of the plurality of contact holes overlaps with one of the plurality of recesses in a vertical direction. 
 
     
     
       5. The organic EL display panel according to  claim 4 , wherein
 at least a portion of each of the plurality of recesses that overlaps with one of the plurality of contact holes extends through the planarizing film, and 
 each of the plurality of cell-electrode layers is in contact with the wiring layer via a corresponding one of the plurality of contact holes. 
 
     
     
       6. The organic EL display panel according to  claim 4 , further comprising:
 an insulating protection film disposed between an upper surface of the wiring layer and a lower surface of the planarizing film, wherein 
 the insulating protection film includes openings that each coincide with at least a portion of one of the plurality of contact holes, and 
 an area of each of the openings in the insulating protection film is less than an area of each of the plurality of recesses in the planarizing film. 
 
     
     
       7. The organic EL display panel according to  claim 4 , wherein
 a planar area of a top opening of each of the plurality of recesses is greater than a planar area of a top opening of a corresponding one of the plurality of contact holes, whereby the top opening of each of the plurality of recesses overlaps with the top opening of the corresponding one of the plurality of contact holes. 
 
     
     
       8. The organic EL display panel according to  claim 3 , wherein
 each of the plurality of cell-electrode layers includes a bend that coincides with a peripheral edge of a corresponding one of the plurality of recesses, and 
 each of the plurality of second banks extends beyond the one of the plurality of recesses so that the plurality of second banks cover the bend in each of the plurality of cell-electrode layers in a direction in which the pair of first banks extends. 
 
     
     
       9. The organic EL display panel according to  claim 3 , wherein
 each of the plurality of cell-electrode layers comprises at least one of a metal and a semiconductor. 
 
     
     
       10. The organic EL display panel according to  claim 1 , wherein
 each of the plurality of recesses in the planarizing film is not below the pair of first banks. 
 
     
     
       11. The organic EL display panel according to  claim 1 , wherein
 each of the plurality of recesses in the planarizing film has an edge below a lateral surface of the pair of first banks. 
 
     
     
       12. The organic EL display panel according to  claim 1 , wherein
 the pair of first banks extends linearly. 
 
     
     
       13. The organic EL display panel according to  claim 1 , wherein
 the plurality of organic light-emitting layers in the plurality of light-emitting cells each comprise a light-emitting material of a same color. 
 
     
     
       14. The organic EL display panel according to  claim 1 , wherein
 each of the plurality of recesses has a top opening that defines an upper opening in an upper surface of the planarizing film and a bottom opening that defines a bottom opening in a bottom surface of the planarizing film, and 
 a planar area of each of the plurality of recesses decreases one of continuously and stepwise from the top opening to the bottom opening. 
 
     
     
       15. The organic EL display panel according to  claim 1 , wherein
 the pair of first banks comprises at least three pairs of first banks, 
 each of the at least three pairs of first banks corresponds to a different one of a red color, a green color, and a blue color, and 
 the plurality of organic light-emitting layers, the plurality of recesses, and the plurality of second banks are disposed between each of the at least three pairs of first banks. 
 
     
     
       16. The organic EL display panel according to  claim 15 , wherein
 each of the plurality of recesses in the planarizing film comprises a first recess, 
 each of the plurality of second banks is concave and includes a second recess in an upper surface, 
 an organic light-emitting material being the same as a material of the plurality of organic light-emitting layers is in the second recess of each of the plurality of second banks, and 
 first volumetric capacities of the first recess and the second recess formed between one of the at least three pairs of first banks are different than second volumetric capacities of the first recess and of the second recess formed between an other of the at least three pairs of first banks. 
 
     
     
       17. The organic EL display panel according to  claim 15 , wherein
 each of the plurality of recesses in the planarizing film comprises a first recess, 
 each of the plurality of second banks is concave and includes a second recess in an upper surface, 
 an organic light-emitting material being the same as a material of the plurality of organic light-emitting layers is in the second recess of each of the plurality of second banks, and 
 first areas of the first recess and the second recess formed between one of the at least three pairs of first banks are different than second areas of the first recess and of the second recess formed between an other of the at least three pairs of first banks. 
 
     
     
       18. The organic EL display panel according to  claim 15 , wherein
 each of the plurality of recesses includes:
 an upper recess portion having a top opening that defines an upper opening in an upper surface of the planarizing film; and 
 a lower recess portion having a bottom opening that defines a bottom opening in a lower surface of the planarizing film, 
 
 an area of the upper recess portion decreases from the top opening toward the bottom opening, 
 an area of the lower recess portion increases from the bottom opening toward the top opening, 
 each of the plurality of recesses includes a step between the upper recess portion and the lower recess portion, 
 a cell-electrode layer extends from each of the plurality of light-emitting cells to a corresponding one of the plurality of recesses and is in electrical connection with the wiring layer via the bottom opening of the corresponding one of the plurality of recesses, 
 one of a first depth and a first area of the individual upper recess portion between one of the at least three pairs of first banks is different than a corresponding one of a second depth and a second area of the upper recess portion between an other of the at least three pairs first banks, and 
 the bottom opening of each of the plurality of recesses between each of the at least three pairs of first banks is uniform. 
 
     
     
       19. The organic EL display panel according to  claim 15 , wherein
 each of the plurality of second banks includes an inclined surface that delimits a lateral surface of a corresponding one of the plurality of organic light-emitting layers, 
 the lateral surface extends in a direction opposite the at least three pairs of first banks, and 
 a first inclination angle of the inclined surface of each of the plurality of second banks between one of the at least three pairs of first banks is different than a second inclination angle of the inclined surface of each of the plurality of second banks between an other of the at least three pairs of first banks. 
 
     
     
       20. The organic EL display panel according to  claim 1 , wherein
 the wiring layer comprises a thin-film transistor layer. 
 
     
     
       21. The organic EL display panel according to  claim 1 , wherein the organic EL display panel is included in an organic EL display device. 
     
     
       22. A method for manufacturing an organic EL display panel, comprising:
 forming a planarizing film above a thin-film transistor layer with a flat surface of the planarizing film being above the thin-film transistor layer; 
 forming a pair of first banks above the planarizing film to delimit lateral surfaces of a plurality of light-emitting cells disposed in a row; 
 forming a plurality of light-emitting layers, each of the plurality of light-emitting layers being in one of the plurality of light-emitting cells between the pair of first banks; 
 forming a plurality of recesses in the planarizing film, each of the plurality of recesses being between adjacent ones of the plurality of light-emitting cells and extending between the pair of first banks; and 
 forming, from a same material as the first banks, a plurality of second banks connected to the first banks, each of the plurality of second banks being above one of the plurality of recesses in the planarizing film and having a shape that conforms to a profile of the one of the plurality of recesses, so that the plurality of second banks are lower in height than the pair of first banks. 
 
     
     
       23. The method according to  claim 22 , wherein
 the pair of first banks and the plurality of second banks are formed by:
 applying, to the planarizing film, a bank material for forming the pair of first banks and the plurality of second banks; and 
 exposing the bank material to light via a mask pattern that is patterned to leave the pair of first banks and the plurality of second banks, and 
 
 each of the plurality of second banks concaves into a corresponding one of the plurality of recesses in the planarizing film by conforming to the inner profile of the corresponding one of the plurality of recesses, so that the plurality of second banks are lower in height than the pair of first banks. 
 
     
     
       24. The method according to  claim 23 , wherein
 the mask pattern is patterned to leave each of the plurality of second banks to have a planar area that is greater than a planar area of each of the plurality of recesses. 
 
     
     
       25. The method according to  claim 22 , wherein
 the plurality of recesses are formed by exposing the planarizing film to light via a mask pattern that is patterned to form the plurality of recesses, and 
 the mask pattern is a multi-tone mask pattern having a plurality of light-transmitting portions with different transmittances. 
 
     
     
       26. The method according to  claim 25 , wherein
 when forming the plurality of recesses, first regions of the planarizing film where the plurality of recesses are formed are exposed to the light via the multi-tone mask pattern, so that second regions where contact holes are to be formed and surrounding regions are exposed to light at different intensities, whereby each of the plurality of recesses is formed to include a step. 
 
     
     
       27. The method according to  claim 22 , further comprising:
 the pair of first banks and the plurality of second banks are formed by:
 applying, to the planarizing film, a bank material for forming the pair of first banks and the plurality of second banks; 
 exposing the bank material to light via a mask pattern that is patterned so that regions of the bank material where the pair of first banks and the plurality of second banks are to be formed are exposed to light of a uniform intensity. 
 
 
     
     
       28. The method according to  claim 22 , further comprising:
 forming, before forming the pair of first banks and the plurality of second banks, a plurality of cell-electrode layers above the planarizing film, each of the plurality of cell-electrode layers coinciding with one of the plurality of light-emitting cells, wherein 
 each of the plurality of cell-electrode layers is formed to include a part of an edge portion located inside a corresponding one of the plurality of recesses, and 
 each of the plurality of second banks is formed to cover the part of the edge portion of a corresponding one of the plurality of cell-electrode layers. 
 
     
     
       29. The method according to  claim 28 , wherein
 each of the plurality of cell-electrode layers is formed to extend from a corresponding one of the plurality of light-emitting cells to inside a corresponding one of the plurality of recesses after a bend at a location coinciding with a peripheral edge of the corresponding one of the plurality of recesses, 
 a mask pattern is used to form the plurality of second banks, the mask pattern being patterned to form each of the plurality of second banks as having a planar area that is greater than a planar area of each of the plurality of recesses, and 
 the plurality of second banks are formed to cover the bend in each of the plurality of cell-electrode layers.